Sounds like a potentially very stupid idea, and I'd be surprised if it got past 'elfun safety. If the thief is semi on the ball, he'll be wearing a lid, and the noise dampened - no scare there. Suffice to say.....I'm out!

You could get around any 'fox traps' with clear warning signs on your property. Farmer next to me has been using them for years and has caught all sorts of things in them, foxes, wabbits, poachers (yep!), sheep theives! Never got prosecuted because he had clear signs that were lit up at night.